Report on Manam (Papua New Guinea) — October 1981
Scientific Event Alert Network Bulletin, vol. 6, no. 10 (October 1981)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Incandescent tephra, glow, ash plume
Please cite this report as:
Global Volcanism Program, 1981. Report on Manam (Papua New Guinea) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 6:10. Smithsonian Institution.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"Both craters showed stronger activity in October. Incandescent tephra ejections from Southern crater were seen on four nights at the beginning of the month, and on most nights from 12 October onwards. Brown or grey ash emissions from Southern crater were seen 1-9 and 21-30 October. Main crater emitted brown or grey ash on most days 1-22 October. Main crater glow was seen on 1 October, and incandescent tephra ejections on the 14th. A substantial ash plume from Main crater (reportedly several tens of kilometers long) was observed on 14 October. White and blue vapours were emitted from both craters during non-explosive intervals throughout October, and rumbling sounds from the volcano were heard on most days. No trends were shown by tiltmeter measurements, and seismic activity remained steady."
Geologic Background. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche valleys" channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.
Information Contacts: C. McKee, RVO.